Refrigeration



July 4, 1939.

sIM. sAcKs'rRo REFRIGERATION Filed June 16, 1956 i ATTORNEY.

ill

Patented July 4, 1939 REFRIGERATION Sigurd Mattias Backstrijm,

Stockholm, Sweden,

assignor, by mesne assignments, to Servel, Inc., New York, N. Y., a corporation of Delaware Application June 16, 1936, Serial No. 85,485 In Germany June 20, 1935 15 Claims.

My invention relates to refrigeration, and more particularly to a method and apparatus for maintaining an enclosed space substantially at a desired temperature with the aid of refrigeration apparatus.

The object of my invention is to provide an improved apparatus for maintaining an enclosed space substantially at a desired temperature with the aid of heating means and refrigeration apparatus.

Another object of my invention is to provide an improved method and apparatus for maintaining an enclosed space substantially at a'desired temperature in which refrigeration apparatus operated by heat, after not being in operation, shall be efiective to cool the enclosed space in the minimum length of time after the operation of the .apparatus is initiated following a heating period.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the claims. The invention itself, however, both as to organization and method, together with further objects and advantages thereof, will be better understood by reference to the following description taken in connection with the accompanying drawing in which the single figure is a diagrammatic illustration of an embodiment of my invention for electrically heating an enclosed space and refrigeration apparatus operated by heat.

Referring to the single figure of the drawing, I have shown a cooling element l and a heating element I l arranged within an enclosed space 12, such as, for example, the thermally insulated storage compartment of a refrigerator cabinet l3. It is to be understood, however, that other arrangements of a cooling element and a heating element can readily be made for maintaining an enclosed space substantially at a constant or desired temperature. In air conditioning systems, "for example, the cooling and heating elements may assume other forms and may be arranged in any suitable manner, as in a duct through which air is drawn or forced, to maintain an enclosure substantially at a constant temperature.

The cooling element l0 forms part of refrigeration apparatus comprising a generator l4 containing a refrigerant in solution in absorption liquid. Although I do not Wish to be limited thereto, the refrigerant may be ammonia and the absorption liquid may be water. The generator 14 is provided with an upwardly extending pocket 15 within which is arranged an electrical heating element Hi. The heat applied to the generator and its contents by the heating element Hi expels the ammonia out of solution, and the ammonia vapor thus generated flows upwardly through an air cooled rectifier I! which condenses any water vapor which may be carried upward with the ammonia vapor. The water condensed in the rectifier drains back to the generator, and the ammonia vapor flows upward to an air cooled condenser i8 comprising a coil provided with a plurality of heat dissipating elements or cooling fins 18. The ammonia is liquefied in the condenser |8 by surrounding cooler air which flows over the surfaces of the coil and fins, and the liquefied ammonia flows through a conduit IS into a conduit 20 communicating with one end of the evaporator or cooling element ID, the conduit l9 being U-shaped at 2| to provide a liquid seal.

The cooling element I!) may comprise a coil (not shown) arranged within a shell 22 provided with trays 23 for freezing water. An inert gas, such as hydrogen, flows from conduit 24 into the end of the cooling element opposite to that into which liquid ammonia is admitted. The hydrogen and liquid ammonia are in counter-flow, therefore, and the ammonia evaporates and diffuses into the hydrogen with consequent absorption of heat from the surroundings of the cooling element in the storage compartment I2. The resulting gas mixture of ammonia and hydrogen, that is, gas strong in ammonia, flows from the cooling element l0 through conduit 20 which communicates at its lower end into the lower end of an absorber 25 comprising an enclosed vessel provided with a coil 26 through which a suitable cooling medium, such as water, may be circulated.

The ammonia is absorbed out of the strong gas mixture into weak absorption liquid which enters the upper part of the absorber through a vertically extending conduit 21. The absorber may be provided with a plurality of distributing plates or baffles (not shown) to insure the absorption of ammonia into the weak absorption liquid, and the hydrogen, which is practically insoluble and weak in ammonia, passes upwardly from the absorber 25 through conduit 24 into the cooling element H]. The conduits 20 and 24 are preferably in thermal contact or heat exchange relation, as diagrammatically shown in the drawing, so that heat is transferred from weak gas entering the cooling element through conduit 24 to the strong gas leaving the cooling element through conduit 20.

The absorption liquid flowing downward through the absorber 25 in counter-flow to the gas mixture becomes enriched in ammonia and passes through conduit 28 and an inner conduit 29 of a liquid heat exchanger 30 to a coil 3| disposed about the lower end of the pocket I5. The strong absorption liquid is heated in the coil 3i by the electrical heating element l6 and is raised by thermo-syphon action from the coil through conduit 32 into the upper part of the generator M. The absorption liquid is raised to a higher levelin the generator I than it is in the absorber 25, and absorption liquid weak in ammonia flows from the lower end of the generator through a conduit 33, outer conduit 34 of the liquid heat exchanger 30 and vertical conduit 21 into the upper end of the absorber 25. Refrigeration apparatus of this type is generally described in Patent No. 1,609,334 to B. C. von Platen and C. G. Munters.

During normal operation of the above-described refrigeration apparatus, heat must be applied to the generator l4 and its contents at or above a predetermined rate by the resistor or heating element IS in order to heat the refrigerant to its vaporization temperature or boiling point so that refrigerant will be vaporized and expelled out of solution from the absorption liquid. When the enclosed space l2 tends to fall below the desired temperature and heat is no longer applied to the generator, the generator and its contents are cooled by the surroundings. Subsequently, when the enclosed space tends to rise above the desired temperature and the operation of the refrigeration apparatus is again initiated, heat must be applied to the generator l4 and its contents by the heating element NS for a relatively long period of time before refrigerant is heated to its vaporization temperature and expelled out of solution from the absorption liquid.

In accordance with my invention, in order to reduce the time that effective cooling is obtained after operation of the refrigeration apparatus is initiated, the resistors or heating elements II and I6 are so arranged that, during a heating period of the enclosed space l2, the application of heat to the generator is not discontinued but modified to apply heat to the generator at such a rate that heat of liquid is supplied to the refrigerant to heat the refrigerant to a temperature slightly below its vaporization temperature. In this manner, when a heating period is termimated and the operation of the refrigeration apparatus is again initiated, the refrigerant is heated to its'vaporization temperature in a relativeiy short time and the cooling element [I'll is efieotive substantially immediately to maintain the enclosed space at the desired temperature.

T is may be accop ti and by connecting the s relation across a ly indicated at E3.

a lesistoi o to the neganve oi the source of supply and the opposite terminal thereof is connected through a corn ductor 3 1 thermal switch disposed Within the storage compartment 92, and conductor to the positive terminal of the source of supply I'he thennal switch a?) comprises a mercury thermometer within the upper end of which is disposed an iron or steel rod 41 which is connected to the conductor 44. The conductor 46 extends into the lower end of the thermometer in a region always occupied by the mercury filling 49 of the thermometer.

The steel rod 41 may be displaced at will vertically, as by a strong magnet, for example, to regulate the predetermined or desired temperature at which the circuit of the electromagnet 39 is completed through the thermal switch 45. In order to suppress any-tendency of sparking in the thermal switch 45, due to the inductance of the electromagnet 39, the mercury filling of the thermometer is preferably connected to the positive terminal of the source of supply 35 and the resistor 43 is connected in the circuit of the electromagnet 39. The tendency of sparking in the thermal switch is further suppressed by connecting resistor 50 in series relation with the thermal switch 45 and electromagnet 39. In order that the electromagnet will require as little current as possible to attract the metal member 4 40 downwardly, thereby reducing the inductance of the electromagnet and any tendency of sparking in the thermal switch 45, the metal member 40 is preferably formed of a metal including iron or steel and having a mean specific gravity which is greater than that of iron or steel and close to that of mercury.

The operation of the apparatus just described is substantially as follows:

When the enclosed space l2 tends to fall below the desired temperature, the rod 41 is out of contact with the mercury filling 49 and the electro magnet 39 remains deenergized. With the electromagnet 39 deenergized, current flows from the source of supply 35 through both of the resistors or heating elements it and it. The resistors H and it are so proportioned that, while the resistor H is effective to supply heat to the enclosed space 52, the current flowing through the resistor M5 is of such magnitude that the heat developed will heat the generator i and its contents to supply heat of liquid to the refrigerant in solution in the absorption liquid The amount desired of th Pi rigeran absorption liquid. Since viously Was at a temperature just slightly below cool the enclosed space 52 substantially immedisistors serving atelyafter its operation is initiated in response to the action of the thermal switch 45.

While I have shown and described one embodiment of my invention, such variations and modifications are contemplated as fall Within the true spirit and scope of my invention, as pointed out in the following claims.

What is claimed is:

1. A method of maintaining an enclosed space substantially at a desired temperature with the aid of absorption refrigeration apparatus including agenerator and a cooling element, which consists in heating absorption liquid in said generator at or above a predetermined rate to expel a fluid out of solution therefrom and produce a refrigerating effect in said cooling element to effect cooling of the enclosed space when cooling is necessary to maintain the desired temperature, heating the enclosed space when heating is necessary to maintain the desired temperature and, while the enclosed space is being heated, heating absorption liquid in said generator below the predetermined rate so that, when it is again desired to produce a refrigerating effect in said cooling element to effect cooling of the enclosed space, the length of time required to heat said absorption liquid at or above the predetermined rate to expel said fluid out of solution therefrom will be reduced.

2. Apparatus for maintaining an enclosed space substantially at a desired temperature including a refrigeration system operated by heat, means including a plurality of resistors serving as heating elements for operating said system andheating the enclosed space, respectively, and means responsive to the temperature of the enclosed space for rendering one of said heating elements capable of operating said system when cooling is necessary to maintain the desired temperature, and for rendering the other of said heating elements operative when heating is necessary to maintain the desired temperature.

3. Apparatus for maintaining an enclosed space substantially at a desired temperature including a refrigeration system operated by heat, means for heating said system and the enclosed space comprising a circuit including at least two reas heating elements, means for energizing said circuit, and means responsive to the temperature of the enclosed space for maintaining both of said heating elements in circuit to render one of said elements operative when heating is necessary to maintain the desired temperature, and for short-circuiting said space heating element to render the other of said elements capable of operating sahi system when cooling is necessary to maintain the desired temperature.

4. Apparatus for maintaining an enclosed space substantially at a desired temperature comprising absorption refrigeration apparatus including a generator and an evaporator, means including said' evaporator for cooling the enclosed space when heat is applied to said generator at or above a predetermined rate, means for heating the enclosed space, means for heating said generator, and means responsive to the temperature of the enclosed space for rendering said generator heat-' to apply heat to said gening means operative predetermined rate when erator at or above the cooling is necessary to perature, and for rendering said space heating means operative when heating is necessary to maintain the desired temperature, said last-mentioned means being capable of rendering said generator heating means operative to apply heat to maintain the desired temsaid generator below the predetermined rate while said space heating means is being operated so that, when said generator heating means is again rendered operative to apply heat to said generator at or above the predetermined rate, the length of time required toeffect cooling will be reduced.

5. Apparatus for maintaining an enclosed space substantially at a desired temperature comprising absorption refrigeration apparatus including a generator and an evaporator, means including said evaporator for cooling the enclosed space when heat is applied to said generator at or above a predetermined rate, means for heating said generator and'the enclosed space, and means responsive to the temperature of the enclosed space for rendering said heating means operative to apply heat to said generator at or above the predetermined rate when cooling is necessary to maintain the desired temperature, and for rendering said heating means operative to heat the enclosed space when heating is necessary to maintain the desired temperature, said last-mentioned means being capable of rendering said heating means operative to apply heat to said generator below the predetermined rate while the enclosed space is being heated so that, when said heating means is again rendered operative to apply heat to said generator at or above the predetermined rate, the length of time required to effect cooling will be reduced.

6. Apparatus for maintaining an enclosed space substantially at a desired temperature comprising absorption refrigeration apparatus including a cooling element and a generator containing a body of absorption liquid having a refrigerant in solution therein, means including said cooling element for cooling the enclosed space when heat is applied to said generator at or above a predetermined rate to expel refrigerant out of solution from said absorption liquid, means for heating said generator and the enclosed space, and means responsive to the temperature of the enclosed space for rendering said heating means operative to apply heat to said generator at or above'the predetermined rate when cooling is necessary to maintain the desired temperature, and for rendering said heating means operative to heat the enclosed space when heating is necessary last-mentioned means also being capable of rendering said heating means operative to apply heat to said generator below the predetermined rate While the enclosed space is being heated so that, when said heating means is again rendered operative to apply heat to said generator at or above the predetermined rate, the length of time required to heat. said absorption liquid to expel refrigerant out of solution therefrom and effect cooling will be reduced.

'7. Apparatus for maintaining an enclosed space substantially at a desired temperature comprising absorption refrigeration apparatus including a cooling element and a generator containing a body of absorption liquid having refrigerant insolution therein, means including said cooling ele- 'ment for cooling the enclosedspace when "heat is applied to said generator to heat said refrigerant in solution in said absorption liquid to its vaporization temperature; means for heating said generator and the enclosed space, and means responsive to the temperature of the enclosed space for rendering said heating means operative to apply heat to said generator to heat said refrigerant in solution in said to maintain the desired temperature, said absorption liquid to its I vaporization temperature to effect cooling of the enclosed space when cooling is necessary to maintain the desired temperature, and for rendering said heating means operative to heat the enclosed space when heating is necessary to maintain the desired temperature, said last-mentioned means also being capable of rendering said heating means operative to apply heat to said generator to heat said absorption liquid and maintain said refrigerant in solution therein below its vaporization temperature so that, when said heating means is again rendered operative to efiect cooling'of the enclosed space, the length of time required to bring said refrigerant in solution in said absorption liquid to its vaporization temperature will be reduced.

8. Apparatus for maintaining an enclosed space substantially at a desired temperature comprising absorption refrigeration apparatus including a generator and a cooling element, said cooling element being effective to cool the enclosed space when heat is applied to said generator at or above a predetermined rate, means including a plurality of resistors serving as heating elements for heating said generator and the enclosed space, and meansresponsive to the temperature of the enclosed space for rendering one of said heating elements operative to apply heat to said generator at or above the predetermined rate when cooling is necessary to maintain the desired temperature, and for rendering the other of said heating elements operative to heat the enclosed space when heating is necessary to maintain the desired temperature, said last-mentioned means being capable of rendering said generator heating element operative to apply heat to said generator below the predetermined rate while the enclosed space is being heated so that, when said generator heating element is again rendered operative to apply heat to said generator at or above the predetermined rate, the length of time required to effect cooling will be reduced.

9. Apparatus for maintaining an enclosed space substantially at a desired temperature comprising absorption refrigeration apparatus including a generator and an evaporator, means including said evaporator for cooling the enclosed space when said refrigerator is heated at or above a predetermined rate, means for heating said generator and the enclosed space comprising a circuit including at least two resistors serving as heating elements, means for energizing said circuit, and means responsive to the temperature of the enclosed space for maintaining both of said heating elements in circuit to render one of said heating elements operative to heat the enclosed space when heating is necessary to maintain the desired temperature, and for short-circuiting said space heating element to render the other of said heating elements operative to heat said generator at or above the predetermined rate when cooling is necessary to maintain the desired temperature, said heating elements being so proportioned that, when said space heating element is operative to heat the enclosed space, said generator heating element heats the generator below the predetermined rate so that, when said space heating element is again shortcircuited, the length of time required to heat said generator at or above the predetermined rate to eifect cooling will be reduced.

areas/so it). In apparatus for heating and cooling a space, a refrigeration system including a heat receiving part and a cooling element in heat transfer relation with said space, said refrigeration system being operative to efiect cooling of said space when said part is heated at or above a predetermined rate, an electric circuit including two heating elements for heating said part and said space, respectively, and means for automaticalyy short circuiting said space heating element, said heating elements being so proportioned that when both of said heating elements are in circuit heat is supplied to said part below the predetermined rate and when said space heating element is short circuited heat is supplied to said part at or above the predetermined rate.

11. In apparatus for heating and cooling a space, a refrigeration system including a heat receiving part and a cooling element in heat transfer relation with said space, an electric circuit including two heating elements for heating said part and said space, respectively, a common source of electrical energy for said elements, and means to vary the magnitude of current in said heating elements.

12. In apparatus for heating and cooling a space, a refrigeration system including a heat receiving part and a cooling element in heat transfer relation with said space, an electric circuit including two heating elements for heating said part and said space, respectively, a common source of electrical energy for said elements, and means to vary the magnitude of current in said heating elements responsive to change in temperature.

13. A method of maintaining a desired temperature with the aid of a refrigeration system operated by heat, which consists in supplying heat to said system at or above a predetermined rate to effect cooling when cooling is necessary to maintain the desired temperature, alternately supplying heat when heating is necessary to maintain the desired temperature and at the same time supplying heat to said refrigeration system below the predetermined rate so that when cooling is again necessary the time delay in operation of said refrigeration system will be reduced.

14. In a method of heating and cooling with the aid of a refrigeration system which produces cooling when supplied with heat above a predetermined rate, the improvement which consists in supplying heat to said system below the predetermined rate while heating is being carried out so that when cooling is again desired time delay in operation of said system will be reduced.

15. Apparatus for heating and cooling a space comprising a refrigeration system including a heat receiving part and a cooling element arranged to cool said space, means for heating said heat receiving part and said space, and means for controlling said heating means to affect the heating of said heat receiving part and said space and thereby control the temperature of said space, said last-mentioned means being constructed and arranged to permit continuous heatheating of said space.

SIGURD MATTIAS BACKSTRdM. 

